[FFmpeg-trac] #3999(ffmpeg:new): Stretching (increasing duration) of video without reencoding

[FFmpeg]

#3999: Stretching (increasing duration) of video without reencoding
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             Reporter:  Ilya87      |                     Type:  defect
               Status:  new         |                 Priority:  normal
            Component:  ffmpeg      |                  Version:  2.4.1
             Keywords:  Stretching  |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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 Summary of the bug:
 How to reproduce:
 {{{
 according to
 https://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video
 % ffmpeg -i input.mp4 -filter:v "setpts=2.0*PTS" -c copy output.mp4

 Filtergraph 'setpts=2.0*PTS' was defined for video output stream 0:0 but
 codec copy was selected.
 Filtering and streamcopy cannot be used together.

 I couldn't make the -r option change situation.

 But as I can understand video duration can be increased without
 reencoding. And this is done in mkvmerge's stretch option: "Stretch this
 track's timecodes. This entry can have two formats. It is either a
 positive floating point number, or a fraction like e.g. 1200/1253. Works
 best on video and subtitle tracks."
 Mkvmerge just changes fps and duration accordingly. In this situation I
 think ffmpeg should check that only setpts filter is set and process video
 without encoding.
 Or there might be another way to do the same thing mkvmerge does?

 ffmpeg version 2.4.1
 built on Sep 22 2014 05:50:26 with gcc 4.9.1 (GCC) 20140903 (prerelease)
 }}}
 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.

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Ticket URL: <https://trac.ffmpeg.org/ticket/3999>
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